Why does a worm need nearly as many genes as a man?

The nematode worm, C. elegans, is the focus of an intense research effort in both developmental biology and genetics because it is one of the simplest multicellular organisms with a nervous system. A new article published in Genome Biology investigates why, despite its apparent simplicity, it needs 20,000 genes when animals as complex as humans make do with only 30,000 or so.